Pericardial modification systems and methods for heart failure treatment

ABSTRACT

This document relates to devices and methods for the treatment of heart conditions. For example, this document provides devices and methods for treating heart failure with preserved ejection fraction, including diastolic heart failure, by performing a pericardial modification procedure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/793,399, filed Feb. 18, 2020, which is a continuation application ofU.S. application Ser. No. 16/406,983 (now U.S. Pat. No. 10,603,062),filed May 8, 2019, which is a continuation application of U.S.application Ser. No. 14/773,487 (now U.S. Pat. No. 10,307,179), filedSep. 8, 2015, which is a National Stage application under 35 U.S.C. §371 of International Application No. PCT/US2014/023081, filed Mar. 11,2014, which claims the benefit of U.S. Provisional Application Ser. No.61/798,382, filed Mar. 15, 2013, and U.S. Provisional Application Ser.No. 61/776,483, filed Mar. 11, 2013. The disclosure of the priorapplications are considered part of (and are incorporated by referencein) the disclosure of this application.

BACKGROUND 1. Technical Field

This document relates to devices and methods for the treatment of heartconditions. For example, this document relates to devices and methodsfor treating heart failure with preserved ejection fraction, includingdiastolic heart failure, by performing a pericardial modificationprocedure.

2. Background Information

The pericardium is the thin double-layered fluid filled sac thatsurrounds the heart and the roots of the aorta, vena cava, and thepulmonary artery. The outer sac is known as the fibrous pericardium. Theinner sac is known as the serous pericardium. The serous pericardiumconsists of a visceral layer portion and a parietal layer portion(“parietal pericardium”). The visceral layer, or epicardium, covers theheart and the great vessels. The parietal portion lines the outerfibrous pericardium.

The phrenic nerves run from the brain to the diaphragm. The phrenicnerves provide motor impulses to muscles of the diaphragm, therebycausing breathing. The right phrenic nerve passes underneath the musclesof the neck and bones of the shoulder to the base of the right lung,contacting the heart and the windpipe. The left nerve follows a similarpath, passing close to the heart before entering the diaphragm.

SUMMARY

This document provides devices and methods for the treatment of heartconditions. For example, this document provides devices and methods fortreating heart failure with preserved ejection fraction, includingdiastolic heart failure, by performing a pericardial modificationprocedure.

In general, one aspect of this document features a method for treatingdiastolic heart failure. The method comprises creating a tent ofpericardial tissue on a heart of a patient, wherein said tent is createdusing a grasping device; creating an opening in said pericardial tissue,wherein said opening is created using a cutting device to cut orpuncture a portion of said tent of pericardial tissue; and relievingpressure exerted by said pericardial tissue on said heart as a result ofcreating said opening.

In some implementations said method for treating diastolic heart failuremay be performed percutaneously. Said grasping device and said cuttingdevice may be catheter-based devices. Said grasping device and saidcutting device may comprise a single catheter-based device. Said methodmay further comprise probing to ascertain a location of a phrenic nerve.At least a portion of said pericardial tissue may be removed from saidpatient.

In general, another aspect this document features a method for treatingdiastolic heart failure. Said method comprises: identifying a patienthaving diastolic heart failure; and creating an opening in saidpatient's pericardial tissue or removing a portion of said patient'spericardial tissue, wherein said creating or said removing reducespressure exerted by said pericardial tissue on said patient's heart.

In some implementations said method for treating diastolic heart failuremay further comprise probing to ascertain a location of a phrenic nerve.

Particular embodiments of the subject matter described in this documentcan be implemented to realize one or more of the following advantages.In some embodiments, heart conditions such as diastolic heart failureand others can be treated using the devices and methods provided herein.In some embodiments, various heart conditions can be treated in aminimally invasive fashion using the devices and methods providedherein. Such minimally invasive techniques can reduce recovery times,patient discomfort, and treatment costs.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention pertains. Although methods and materialssimilar or equivalent to those described herein can be used to practicethe invention, suitable methods and materials are described herein. Allpublications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety. Incase of conflict, the present specification, including definitions, willcontrol. In addition, the materials, methods, and examples areillustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description herein. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of patient undergoing a pericardectomyusing an exemplary catheter-based pericardectomy device system inaccordance with some embodiments provided herein.

FIGS. 1B and 1C are schematic illustrations of another exemplarypericardectomy device system in accordance with some embodimentsprovided herein.

FIGS. 2A-2D are schematic illustrations of a heart after apericardectomy in accordance with some embodiments provided herein.

FIG. 3 is flowchart of a pericardectomy method in accordance with someembodiments provided herein.

FIG. 4 illustrates another pericardial modification device in accordancewith some embodiments provided herein.

FIG. 5 illustrates another pericardial modification device in accordancewith some embodiments provided herein.

FIG. 6 illustrates another pericardial modification device in accordancewith some embodiments provided herein.

FIG. 7 illustrates another pericardial modification device in accordancewith some embodiments provided herein.

FIGS. 8A-8F are a series of illustrations depicting a pericardialmodification procedure in accordance with some embodiments providedherein.

FIG. 9 is a graph that illustrates the results of a pericardialmodification procedure.

Like reference numbers represent corresponding parts throughout.

DETAILED DESCRIPTION

This document provides devices and methods for the treatment of heartconditions. For example, this document provides devices and methods fortreating heart failure with preserved ejection fraction (HFpEF),including diastolic heart failure, by performing a pericardialmodification procedure. The devices and methods provided herein may alsobe used to treat other conditions for which pericardial modifications,including but not limited to removal of all or part of the pericardium,are advantageous. In some implementations, the devices and methodsprovided herein may be used to treat conditions such as increaseddiastolic ventricular interaction, pulmonary arterial hypertension, andright ventricular myocardial infarction, to provide some additionalexamples.

The devices and methods provided herein can also be used to treatpericardium disorders (e.g., pericarditis, pericardial effusion, etc.).In addition, the devices and methods provided herein can also be used onpericardial sacs that are themselves healthy—so as to treat otherrelated conditions, such as HFpFE, including diastolic heart failure.

As used within this document, the term “parietal pericardium,” when usedin the context of incising, dilating, removing, or otherwise modifyingall or portions thereof, is defined to include a corresponding portionof fibrous pericardium. For example, the removal of a strip of parietalpericardium by definition also includes the removal of a correspondingstrip of fibrous pericardium.

In some embodiments using devices and methods provided herein, HFpFE istreated by performing a full pericardectomy. In some embodiments, thetreatment performed is a partial pericardectomy. In some embodiments, nopericardial tissue is removed, but the pericardial tissue is modulatedor otherwise modified in such a way as to remove the constrictive forceof the pericardial sac on the heart. For example, in some embodiments, astrip of the parietal pericardium is removed by cutting, tearing,slitting, expanding, cauterizing, and the like. In some embodiments,holes or tears are made in the pericardial sac, thereby facilitatingdilation of the pericardium. In some embodiments the pericardial sac isslit, expanded, torn, cauterized, cut, or in some other fashionmodulated or modified, to remove the constrictive force of thepericardial sac on the heart.

In some embodiments, only the outer parietal pericardium is modified,modulated, or fully or partially removed. In some embodiments, both theparietal and the visceral layers of pericardium are modified, modulated,or fully or partially removed. In some embodiments, the parietal layeris fully removed and the visceral layer is modified, modulated, orpartially removed.

In some cases, the visceral layer of pericardium can be modified,modulated, or fully or partially removed with or without modifying,modulating, or fully or partially removing the outer parietalpericardium. For example, the visceral layer of pericardium can bemodified or modulated by using DC/RF to soften of the visceral layer.

In some embodiments, the phrenic nerves are detached from the parietalpericardium as part of the pericardial modification procedure. In someembodiments, the phrenic nerves are left attached to a portion of theparietal pericardium that is left remaining on the heart while otherportions of the parietal pericardium are removed.

The devices and methods for pericardial modification provided hereinencompass a range of surgical devices and techniques. In someembodiments, the pericardial modification is performed percutaneously.The approach can be, for example, subxiphoidal or lateral or viathoracotomy. In some cases it may be possible to perform the procedureby entering the heart and puncturing out of the heart through amyocardial wall (e.g. ventricle, atrium, appendage, etc.) to gain accessto the pericardial space (e.g., an inside-out approach). In someembodiments, video-assisted thoracoscopy can be used. In someembodiments, robotic assistance can be used. In some embodiments,open-chest techniques are used. In some embodiments, a combination ofsuch techniques are used.

In some embodiments, cutting of the pericardium is performed from theoutside of the pericardium. In some embodiments, the pericardial sac isinitially punctured by a device, and then the cutting is performed fromwithin the pericardial space in a direction generally outward from hearttissue.

Devices having a variety of functional features are used to perform thepericardial modification methods provided herein. In some embodiments,the devices provided herein are flexible catheter-based grasping devices(e.g., forceps, suction devices, cryo/cooling devices, and/or snares).In some embodiments, the devices provided herein are flexiblecatheter-based cutting devices (e.g., scissors, sheaths, knife, scapel,lasers, snares, cryogenic devices, and electrocautery devices). In someembodiments, the grasping and cutting devices are combined on a singlecatheter device. In some embodiments, the grasping and cutting devicesare separate devices. In some embodiments, the catheter-based devicesprovided herein can install hooks, anchors, and/or clips in a temporarymanner to assist with performing the pericardectomy techniques. In someembodiments, an expandable element (e.g., a balloon, nitinol-baseddevices, etc.) can be used to create a working space in the pericardialsac and to protect the heart or otherwise direct the cutting instrument.

Components for visualizing, probing, and sensing the anatomy may beincluded with the devices provided herein. For example, in someembodiments the devices provided herein include electrode devices forstimulating or sensing the phrenic nerves. In some embodiments, thedevices provided herein include an impedance measurement probe forsensing tissue or nerves. In some embodiments, the devices providedherein include a Doppler probe for visualizing the anatomy. In someembodiments, the devices provided herein include an optical camera forproviding images of internal anatomy. In some embodiments, the devicesprovided herein include thoracoscopy style devices.

Further additional functional features are included in some embodimentsof devices provided for performing the pericardial modification methodsprovided herein. In some embodiments, stabilization devices areincluded. In some embodiments, balloon devices are included. In someembodiments, opposable catheters with magnetic coupling are included. Insome such embodiments, a first catheter can be located within thepericardial space, a second catheter can be located on the exterior ofthe pericardium, and a magnetic coupling between the two catheters canenable them to cooperatively perform a pericardectomy procedure.

With reference to FIG. 1A, a human patient 10 is depicted as undergoinga pericardectomy procedure using an example pericardectomy device 100.Patient 10 has a skin surface 12, and a heart 20 that is encompassed bya pericardium 22.

Example pericardectomy device 100 is a catheter-based device configuredfor percutaneous functionality. That is, pericardectomy device 100 isinsertable through a skin penetration point 14, such as an incision. Insome cases, a trocar device is employed in skin penetration point 14. Insome cases, a delivery sheath or endoscope is installed in patient 10 todirect the placement of the pericardectomy device 100.

While pericardectomy device 100 is depicted as a single catheter, insome embodiments two or more catheter-based devices are used to performthe pericardectomy procedures provided herein. In some cases, multipleskin penetration points may be employed. Still further, in someembodiments, an open-chest procedure, or a thoracoscopy procedure can beused to perform the pericardectomy procedures provided herein.

Example pericardectomy device 100 includes an actuator 110, a flexiblecatheter 120, and an operative distal end 130. In this example,operative end 130 includes a grasping device 132 and a cutting device134. Example pericardectomy device 100 also includes a bipolarconnection 140 for energizing operative end 130.

Some embodiments of the pericardial modification methods provided hereininclude provisions to avoid or minimize dissection or damage toparticular structures such as the phrenic nerves or blood vessels. Tofacilitate avoidance of damage to structures such as the phrenic nerves,some embodiments of operative end 130 include a device such as anelectrode (not shown) that can be used to identify the location of thephrenic nerves. Phrenic nerves control the motor impulses to muscles ofthe diaphragm. When the electrode is in the proximity of the phrenicnerves, electrical pulses generated from the electrode will stimulatemovement of the diaphragm that can be visualized by clinicians. Hence,when electrical pulses delivered by an electrode result in no movementof the diaphragm, it can be determined that the phrenic nerves are notin the immediate vicinity of operative end 130. In such cases, graspingand cutting of the pericardium by operative end 130 can be performed inthe immediate vicinity with a low likelihood of incurring damage to thephrenic nerves.

In some cases, to identify and/or avoid damage to the vessels, analgorithm for vessel identification and turning off energy delivery canbe used. In some cases, sensors such as Doppler probes or impedancemeasurements from electrograms can be used. For example, impedance frommyocardium and pericardium can stay stable through the cardiac cycle forthe most part, but a characteristic phasic variation can occur in anyhollow viscus or as a result of change with contact or pressure orinternal diameter. This can occur in arteries and can be used identifyquickly where arteries are when a device provided herein is placed intoposition.

In some embodiments, squeezing the two handles 112 together can closethe grasping device 132 to secure a portion of the pericardium 22. Insome embodiments, grasping device 132 is a forceps, and the jaws of theforceps can be closed by squeezing handles 112 together. In someembodiments, grasping device 132 can perform both grasping and cuttingoperations. For example, grasping device 132 can be configured to grasppericardium 22 using an initial amount of clamping force, and byapplying a greater amount of force the jaws of grasping device 132 cancut through pericardium 22.

In some embodiments, grasping device 132 is a suction member that canretract pericardium 22. The suction force can be applied to pericardium22 in a controllable fashion using actuator 110. In some embodiments,other suitable types of grasping devices 132, including cryogenicdevices, are included with pericardectomy device 100.

In some embodiments, grasping device 132 is an electrocautery device. Insuch embodiments, a single grasping device 132 can grasp, sever, andcauterize pericardium 22. Bipolar connection 140 can be connected to anenergy source, such as a RF cautery system power supply. Theelectrocautery operation can be initiated by a clinician operator usingactuator 110, such as by pushing a button 116.

In some embodiments, some or all of catheter 120 is steerable. Forexample, in some embodiments operative end 130 is steerable usingactuator 110. In some such embodiments, grasping device 132 can becanted away from heart 20 to create a pericardium tent 24. That is,after grasping device 132 has secured a portion of pericardium 22, theclinician operator of pericardectomy device 100 can steer operative end130 to pull pericardium 22 away from heart 20 to create a tent-likeportion of pericardium 24.

In some embodiments, a balloon device (not shown) can be used to createpericardium tent 24. For example, an un-inflated balloon can bepositioned in the pericardial space. Then the balloon can be inflated tocreate pericardium tent 24. In some embodiments, the inflation of theballoon can be used to expand or tear a hole or incision that was madein the pericardium.

In some embodiments, one side of the balloon device can include one ormore RF electrodes. The side of the balloon with the one or more RFelectrodes can be positioned abutting the underside of pericardium 22.The RF electrodes can be activated to damage parietal pericardium.Alternately, the orientation of the balloon can be reversed and the RFelectrodes can perform ablation of the epicardial pericardium.

Pericardium tent 24 facilitates the isolation of a portion ofpericardium 22 so that the cutting of pericardium 22 can occur with lessrisk of damaging other tissues. In some embodiments, a stabilizingdevice (not shown) can also be used to reduce movement of pericardium 22in preparation for cutting.

Cutting device 134 can be located at a position at operative end 130 tocooperate with grasping device 132. For example, in some embodiments,cutting device 134 is locatable between the jaws of grasping device 132.In some embodiments, cutting device 134 is locatable adjacent tograsping device 132. In this manner, cutting device 134 can be inposition to cut pericardium tent 24 created by grasping device 132. Insome embodiment, cutting device 134 is locatable and maneuverableindependent of grasping device 132.

Cutting device 134 can be actuated by a clinician operator usingactuator 110. For example, in some embodiments pulling a trigger 114 canoperate cutting device 134. In some embodiments after cutting, theexposed edges of pericardium 22 can be cauterized using pericardectomydevice 100.

A variety of types of cutting devices 134 can be used. In someembodiments, cutting device 134 is a scissors tool. In some embodiments,cutting device 134 is a scalpel blade. In some embodiments, the tip(s)of cutting device 134 have sharp points. In some embodiments, the tip(s)of cutting device 134 have blunt points. In some embodiments, cuttingdevice 134 is a snare or lasso that can be positionally maneuveredaxially and radially on catheter 120. The snare can be used to captureand cinch portions of pericardium tent 24, and then cut it. In someembodiments, the snare can also cauterize pericardium 22. In someembodiments, other suitable types of cutting devices are used onpericardectomy device 100.

In some embodiments, the pericardial sac 22 is initially punctured by adevice (e.g., grasping device 132 or cutting device 134), then thecutting is performed from within the pericardial space, and in adirection generally outward and away from heart tissue.

In some embodiments of pericardectomy device 100, two opposing cathetersare used. One catheter can have its tip positioned in the pericardialspace to create pericardium tent 24. A second catheter can be locatedexternal to the pericardial space and can perform grasping/cuttingoperations on pericardium tent 24. In some embodiments, the opposingcatheters are magnetically coupled to each other to coordinate theirrelative positions in an advantageous manner. In some embodiments, theopposing catheters are mechanically coupled together, or in othersuitable manners, to coordinate their relative positions.

After a single cut or multiple cuts to pericardium 22 have been made,pericardectomy device 100 can be repositioned to another area ofpericardium 22 as desired. The actions can be repeated to cut (or tear,puncture, dissect, etc.) another portion of pericardium 22. By repeatingthe actions described herein, pericardium 22 can be removed to theextent desired—which may be a full or partial removal of pericardium 22.

With reference to FIGS. 1B and 1C, another example pericardectomy device150 is provided. Pericardectomy device 150 includes two graspers 160 aand 160 b that flank the position of a central electrocautery tissuecutter 170. In some embodiments, the orientation of graspers 160 a-b tocutter 170 can be controlled by a coupler 175, or in some embodiments byan over-tube device. In some embodiments, coupler 175 is fixedly coupledto cutter 170 and slidably coupled to graspers 160 a-b. In someembodiments, an endoscope and light source are included withpericardectomy device 150. In some embodiments, central electrocauterytissue cutter 170 is also used as a probe that is used to stimulate thephrenic nerve so as to detect and map the location of the phrenicnerves.

In some embodiments, pericardectomy device 150 can include one or moreelectrodes that can be used to trace electrical potentials on tissuessuch as the pericardial tissue. In some implementations, such tracing ofelectrical potentials can be useful for navigation of pericardectomydevice 150 within the patient.

In some embodiments, graspers 160 a-b are over-the-wire grasping tools.In other words, graspers 160 a-b can be installed over a guidewiredevice. In some embodiments, graspers 160 a-b are configured for amonorail-type guidewire system. In some embodiments, graspers 160 a-bare configured for a central wire advancement guidewire system. That is,graspers 160 a-b can include a longitudinal lumen that can slidablyreceive a guidewire, or graspers 160 a-b can include a collar (e.g.,refer to FIGS. 4 and 5 ) that can slidably receive a guidewire. In someembodiments, only one jaw of graspers 160 a-b is pivotable, while theother jaw is fixed. In some embodiments, both jaws of graspers 160 a-bare pivotable.

In some embodiments, the longitudinal lumen of graspers 160 a-b that areso equipped can be used to convey a contrast media for fluoroscopy. Insome such embodiments, the lumen can be confluent with the jaws ofgraspers 160 a-b. When pericardectomy device 150 is in use, the contrastmedia can be used to visualize that one jaw of graspers 160 a-b is abovethe pericardium and the other jaw is below the pericardium as desired.That is, the jaw beneath the pericardium can be visualized by thecontrast media being contained within the pericardial space, and the jawabove the pericardium can be visualized by the contrast media beingdispersed outside of the pericardial space. In some embodiments,contract media can be delivered through one to or both graspers 160 a-bwhile graspers 160 a-b are engaged with pericardial tissue. Thisdelivery of contrast media can stain the pericardial tissue to enhancethe radiographical visualization thereof.

To maneuver pericardectomy device 150 into position near the outersurface of the patient's pericardium, first the guidewire can bepercutaneously installed. After installing the guidewire to thepericardial space, a first grasper 160 a can be advanced over theguidewire, and the grasper 160 a can be clamped onto a portion ofpericardium. Then grasper 160 a can be detached from the guidewire(assuming a monorail-type guidewire system). The second grasper 160 bcan then be advanced over the same guidewire, and clamped onto a portionof pericardium adjacent to the other grasper 160 a. Then a singleovertube device or coupler 175 can be installed onto the shafts ofgraspers 160 a-b. Coupler 175 can include a central cutting tool such aselectrocautery tissue cutter 170. Electrocautery tissue cutter 170 canbe advanced to the area of graspers 160 a-b. Alternatively, in someimplementations two or more guidewires can be utilized. In some suchimplementations, graspers 160 a-b and tissue cutter 170 can thereby beadvanced over guidewires that are distinct from each other.

The general operation of pericardectomy device 150 can be as follows(this description assumes that pericardectomy device 150 is alreadywithin a patient and near the outer surface of the patient'spericardium). A clinician can manipulate graspers 160 a-b to advancethem beyond cutter 170 as shown in the configuration of FIG. 1B.Graspers 160 a-b can slide in relation to coupler 175 (or an overtubedevice) to thereby advance beyond cutter 170. Graspers 160 a-b can beused to grasp or pinch a portion of the pericardium. With portions ofpericardial tissue contained within the jaws of graspers 160 a-b, apericardial tent is formed between graspers 160 a-b.

Next, cutter 170 can be advanced by the clinician to a locationgenerally adjacent to graspers 160 a-b as shown in FIG. 1C. A probe 172of cutter 170 can puncture the pericardial tent. Then a jaw 174 ofcutter 170 can be pivoted by the clinician to come into contact with thepericardial tent. Energy for bi-polar electrocauterization can bedelivered to cutter 170 to sever and cauterized the pericardial tissuecontained between probe 172 and jaw 174. After the cutting, theclinician can open the jaws of graspers 160 a-b, and then advancegraspers 160 a-b to the next desired location to be cut. Theconfiguration of pericardectomy device 150 can then once again resembleFIG. 1B. The process steps above can be repeated until the pericardialcutting is completed to the extent desired.

After completion of the cutting process, or at one or more times duringthe cutting process, portions of pericardial tissue can be severed andremoved from the patient. This severing and removal of the pericardialtissue can be performed using various techniques. In one example, abipolar snare tool (not shown, but similar to those devices used forremoving polyps) can be advanced over graspers 160 a-b while graspers160 a-b are holding pericardial tissue. The bipolar snare tool can beadvanced beyond the distal end of graspers 160 a-b and into contact withthe pericardial tissue. The bipolar snare tool can be activated whilethe graspers 160 a-b continue to hold the pericardial tissue. After theenergy from bipolar snare tool has severed a portion of the pericardialtissue, graspers 160 a-b can be withdrawn from the patient while theportion of the pericardial tissue is in the jaws of graspers 160 a-b.

FIGS. 2A-2D illustrate various example partial pericardium 22 removalpatterns. These patterns are provided to convey an understanding of thevariety of end results that can be achieved using the devices andmethods provided herein. In some scenarios, the patterns can be combinedin a single case. Other types of patterns, as well as removal of thefull pericardium 22, are also envisioned within the scope of thisdocument.

FIGS. 2A and 2B illustrate heart 20 that has had a strip 26 ofpericardium 22 removed. The area of strip 26 exposes the epicardialpericardium or the heart tissue (in such cases when the epicardialpericardium has also been removed). Strip 26 of pericardium 22 has beenremoved using the devices and methods provided herein.

FIG. 2A depicts strip 26 running generally from the apex of heart 20 andin a generally superior/inferior direction. FIG. 2B depicts strip 26running around the middle of heart 20, and in a generally transverseposterior/anterior direction. In some cases, strip 26 runs all the wayaround heart 20 (including posterior portions on heart 20 not visible inFIGS. 2A and 2B). In some cases, strip 26 runs partially around heart 20(e.g., generally as shown, or in a shorter segment than shown). Allcombinations of directions and lengths of strip 26 are envisioned withinthe scope of this document.

Measures can be taken to inhibit or prevent the reformation of tissue(e.g., scar tissue) across strip 26. In some cases, the width of strip26 can be made sufficiently wide to inhibit or prevent the reformationof tissue across strip 26. For example, in some cases making the widthof strip 26 from about 0.5 cm to about 1 cm, or about 0.75 cm to about 2cm or more can inhibit or prevent the reformation of tissue across strip26. In some cases, the edges of pericardium 22 can be cauterized toinhibit or prevent the reformation of tissue across strip 26. In somecases, the cut edges of pericardium 22 can be doubled over.

In cases where portions of the parietal pericardium are removed but thevisceral pericardium remains, measures can be taken to inhibit orprevent attachment of the parietal and visceral pericardial layers thatmight otherwise create smaller but significant pericardial spaces again,thereby causing restraint in diastole. For example, attachment of theparietal and visceral pericardial layers can be inhibited or preventedby removing a significant amount of the parietal pericardium. In suchcases, strip 26 can be made wider to decrease the propensity forattachment of the parietal and visceral pericardial layers.

FIG. 2C illustrates another pattern for partial removal of pericardium22. That is, pericardium from an inferior portion 27 has been removed.The removal can include only the parietal layer, or both the parietaland visceral pericardial layers of pericardium 22.

In some embodiments, the methods of performing pericardectomy providedherein can begin by removing portions of pericardium 22 near the apex 29of heart 20. For example, a generally circular section of pericardium 22can be removed at apex 29. In some embodiments, this technique can beused advantageously to avoid the phrenic nerves. If additional removalof pericardium 22 is desired (e.g., if additional diastolic pressureremoval is desired), further removal of pericardium 22 can be propagatedfrom the region removed at apex 29. In some embodiments, pericardium 22covering the left and right ventricles, or substantial portions thereof,are removed.

FIG. 2D illustrates another pattern for partial removal of pericardium22. The pattern is made by creating multiple incisions, tears, orremovals of pericardium 22 to create the multiple openings 28. Thispattern can allow the volume contained by pericardium 22 to expand. Insome embodiments, this method and pattern can be used to relievepressure within pericardium 22, thereby treating conditions such asHFpFE. The shape of openings 28 can be anything that allows pericardium22 to expand, e.g., ovals, circles, squares, rectangles, slits and thelike. Any suitable quantity of openings 28 can be created. Openings 28can be located in pericardium 22 anywhere on heart 20 as desired(including posterior regions not shown).

An additional method for partial removal of pericardium 22 can beperformed as follows. The pericardial space can be entered by a catheterdevice, and two small hooks, clamps, or other retention devices (e.g.,an Amplatzer-like device) can be installed to the pericardium. A cut tothe pericardium can be made, and the catheter device can be positionedbetween the two small retention devices that were installed in thepericardium. Then the pericardium can be rolled up in a lateraldirection by rotary action of the catheter device to create a bundle ofpericardium—until a phrenic nerve is reached. The rolling can be stoppedas soon as phrenic nerve stimulation is observed. Next, an outer sheaththat acts as a cutting tool is placed around the bundle of pericardium.The cutting of the pericardium bundle will remove the pericardiumportion and release the catheter device simultaneously.

In some cases, a clamp device can be used to help hold a portion of apericardium in a region near an entry site. For example, a clampingdevice configured to be similar to an Amplatzer with larger patches inplace of discs can be used to clamp at least a portion of a pericardium.In some cases, the two large patches can be connected between the centerof the patches and/or along an outer perimeter of the patches. Once aclamp device is deployed, a user can tug on the clamp device to gain asecure hold on the pericardium and then insert an overtube that can beconfigured to cut the pericardium. In some cases, a clamp device can beused to enter the pericardium, and then poke back out of thepericardium. In some cases, two different clamp devices can be used attwo different sites.

In some cases, a spreader device can be used to help increase a gapwithin the pericardial space. In some cases, a spreader device caninclude a number (e.g., 2, 3, 4, 5, 6, or more) expandable petals orblades. Once the spreader device enters the pericardial space with thepetals or blades folded along a central axis of the device andpositioned in a desired location, a balloon can be inflated such thatpetals or blades spread apart creating a gap within the pericardialspace. In some cases, the balloon can be deflated such that the petalsor blades fold along a central axis. In this case, the spreader devicecan be advanced to another position, and the balloon inflated again,thereby creating additional gaps or openings within the pericardialspace. In some cases, one or more petals or blades can included acutting component or electrodes that can be used to cut tissue asdesired.

An additional method for partial removal of pericardium 22 can beperformed as follows. The pericardial space can be entered by a catheterdevice, and two small hooks, clamps, or other retention devices (e.g.,an Amplatzer-like device) can be installed to the pericardium. A cut tothe pericardium can be made, and the catheter device can be positionedbetween the two small retention devices that were installed in thepericardium. Then the pericardium can be rolled up in a lateraldirection by rotary action of the catheter device to create a bundle ofpericardium—until a phrenic nerve is reached. The rolling can be stoppedas soon as phrenic nerve stimulation is observed. Next, an outer sheaththat acts as a cutting tool is placed around the bundle of pericardium.The cutting of the pericardium bundle will remove the pericardiumportion and release the catheter device simultaneously.

FIG. 3 is a flowchart of an example embodiment of a method 300 forperforming a pericardial modification using the devices provided herein.In general, method 300 can be performed percutaneously or by anopen-chest procedure. Method 300 can be used to remove all or a partialportion of one or both pericardial layers. Method 300 can be used toremove pericardium that is diseased, and/or pericardium that is healthy.

At operation 310, a device enters the epicardial and/or extraepicardialspaces and is moved into position adjacent to the pericardium. In someembodiments, a catheter-based device is used. In some embodiments, othertypes of surgical devices can be used. In some embodiments, acombination of catheter-based devices and other surgical devices can beused. In some embodiments, the device includes grasping and cuttingfunctionality. In some embodiments, a balloon device is included on thedevice. In some embodiments, sensory functionalities are included on thedevice, such as Doppler, impedance, and pacing probes to provide a fewexamples. In some embodiments, a camera device is included on thedevice. In some embodiments, the device includes electrocautery orcryogenic capabilities. The device may include any combination andsubcombination of such functional features, as well as other featuresthat are advantageous for performing pericardectomy procedures.

At operation 320, a test is optionally performed to confirm that thedevice is in a desired location for cutting the pericardium. Forinstance, phrenic nerves generally located on the sides of the heart canbe advantageously avoided using tests to confirm their location. Forexample, in some embodiments the device can include a pacing probe tostimulate the area of the tip of the device. If the tip of the device isin the proximity of a phrenic nerve, a movement of the diaphragm may beobserved in response to electrical stimulation from the pacing probe. Inother cases, other devices such as a Doppler or impedance probe and thelike may be optionally used to confirm the device is in a desiredlocation for cutting the pericardium.

In some cases, a device provided herein can be positioned such that thedistal end portion is laying adjacent to the targeted layers of thepericardium to be modified to help avoid injuring parts of the mammal'sanatomy other than the pericardium. For example, the distal end portionof a cutting device can be positioned to avoid cutting a phrenic nerve,a coronary vessel, or another sensitive structure.

At operation 330, the pericardium is cut, torn, punctured, burned, orotherwise locally destructed to create an opening in the pericardium. Insome cases, a cutting device is used to sever the pericardium. In somecases, an electrocautery device can be used to burn an opening in thepericardium. In some cases, other devices including lasers, cryogenicdevices, and other cutting tools can be used to create openings in thepericardium.

At operation 340, the edges of pericardium can be optionally cauterized.In some cases, cauterization may beneficially inhibit the reformation ofpericardial tissue across the openings created in the pericardium.

At operation 350, the clinician can determine whether the pericardiumhas been modified as desired, or whether further treatment is desired.When further treatment is desired, for example to make additional cutsin the pericardium to facilitate removal of pericardium, the cliniciancan generally repeat method 300 until the pericardectomy procedure iscomplete.

It is usually very fibrous near the sub-xiphoid space. In some cases,the methods provided herein can include entering into the pericardiumnear the sub-xiphoid access point and then exiting once the deviceprogresses past the fibrous area. For example, a device provided hereincan include a small hypotube that has a hollow needle within it. A wirecan be positioned within the hollow needle. A distal end region of thewire can include an electrode with RF to help pierce through the tissue.

In some cases, a method provided herein can be performed in a mannerthat reduces bleeding and/or pain during and/or after the procedure. Forexample, a pericardial sheath can be used that is coated with an agentthat acts as a sponge (e.g., a chemical sponge) to soak up blood and/orprevent bleeding. In some cases, the agent can be a thrombostatic agent.Examples of coating agents include, without limitation, gelfoam(purified porcine skin gelatin), human thrombin, and bovine thrombin. Insome cases, an RF catheter of a device provided herein can be configuredto elute a steroid, depo-medrone, ionized lidocaine, lidocaine, and/orbupivacaine. Removing the pericardium itself can help reducepost-procedural pain because the pain fibers are being removed alongwith it. In some cases, removal of the pericardium can become adjunct toother procedures (e.g., left atrial appendage closure or intractableangina treatment) to reduce pain. If some of the pericardium is leftbehind, however, (for example, areas near the phrenic nerve), low DCenergy can be delivered to reduce pain fibers. Such energy can bedelivered as described herein.

In some embodiments, the pericardial modification devices and methodsprovided herein involve modification of the pericardium rather thanpericardectomy. Such modification techniques can have value in actuallykeeping the pericardial space and structures intact but greatlyminimizing pericardial restraint. One example pericardial modificationprocedure can be performed as follows.

First, a balloon device can be positioned in the pericardial space. Theballoon device can include electrodes on at least one of the balloon'ssurfaces. Some electrodes can be orientated so they are pointed towardthe pericardial space. Then, those electrode are stimulated for thepurposes of mapping the course of the phrenic nerve. Those electrodesare then taken away from the energy delivering circuit with a switchingsystem.

Other electrodes on the balloon are then used to deliver energy to theparietal pericardium. The energy could be radiofrequency (“RF”),ultrasound, or DC current at either electroporative or ablation doselevels. In some embodiments, the balloon itself can be differentiallyexpandable. That is, the balloon can expand so as to exert substantialpressure against the parietal pericardial surface, but only minimalpressure towards the surface of the heart, to avoid coronarycompression. This pericardial modification method can provide acombination of parietal pericardium dilation, breaking of the fibrouspericardium, and DC/RF softening of the pericardium (which in turnallows more dilation).

In some cases, the methods and devices provided herein can be used toaccess the pericardium using a mediastinal approach, a pericardialwindow, and/or an open pericardial access approach, for example, whensome other surgery is being performed or contemplated. In some cases,the methods and devices provided herein can be used to access thepericardium from the heart itself. For example, the methods and devicesprovided herein can be used to exit the heart, suction in or grasp atleast a portion of the pericardium, and remove it via an endocardialapproach. In such cases, a closure device can be positioned in the exitsite of the heart once the procedure is completed.

In some cases, the methods and devices provided herein can be used tocut or modify the pericardium without extracting the pericardium. Forexample, once cut or modified, the pericardium can be left in the spacein a manner where it can no longer impede myocardial relaxation.

In some cases, a stimulation device can be used to control the phrenicnerve. For example, a sub-threshold stimulation device can be used toimprove diaphragmatic function in patients with diaphragmatic problems.Stimulating the phrenic nerve in a synchronous manner with the cardiaccycle can be performed. For example, a wire placed on both phrenicnerves for cross-shunting purposes can be used to treat unilateralphrenic palsy. In some cases, electrodes can be placed on the phrenicnerve on both sides, and a central wire can be used as a shunt betweenthe two of them. In these cases, if one phrenic nerve is paretic, thenthe impulse from the other phrenic nerve can be shunted down towards thediaphragm.

FIGS. 4-7 illustrate additional devices that can be used to perform thepericardial modification techniques provided herein. It should beunderstood that the features included in one device embodiment can becombined with features from other device embodiments to create hybriddevices. For example, an electrocautery feature depicted on one devicecan be used on another device whether or not such an electrocauteryfeature is depicted on the other device. All other features can besimilarly used in any of the devices whether or not the particularfigure includes such features.

FIG. 4 illustrates another example pericardial modification device 400.Pericardial modification device 400 includes a shaft 410, a collar 420,and an incisor 430. In some implementations, pericardial modificationdevice 400 is used with a guidewire 440 and an introducer sheath 450(shown in longitudinal cross-section). Collar 420 is coupled to shaft410. In some embodiments, collar 420 is coupled to a distal end portionof shaft 410. Collar 420 defines a central opening in which guidewire440 can be slidably received. The distal end of pericardial modificationdevice 400 includes an atraumatic tip. In some embodiments, pericardialmodification device 400 is steerable. In alternative embodiments, shaft410 can include a lumen which can slidably receive guidewire 440 (asshown in FIG. 6 , for example). In some such embodiments, collar 420 isomitted.

In some embodiments, incisor 430 is pivotably coupled to shaft 410.Incisor 430 can be pivoted as indicated by arrow 432. Such pivotingaction can be initiated by a clinician operator at a handle portionexterior to the patient (e.g., refer to FIG. 1A). The pivoting actionallows incisor 430 to perform as a scissors in combination with shaft410 to facilitate incising tissue such as the pericardium. In someembodiments, shaft 410 includes a portion that is complementary toincisor 430 so that an efficient shearing action is achieved. In someembodiments, incisor 430, or shaft 410, or both, may include one or moreelectrocautery electrodes to facilitate modification of the pericardiumand/or cauterization of tissue. In some embodiments, pericardectomydevice 400 can also include nerve stimulation capabilities to assistwith identification of nerve locations.

In some embodiments, incisor 430 and/or shaft 410 may include one ormore electrodes 434 and 412 respectively to assist with nerveidentification. For example, in some implementations electrodes 434and/or 412 may be useful for identification of the location of phrenicnerves and other nerves. Alternatively, or additionally, electrodes 434and 412 may be used to sense electrical signals from the left atrialappendage and/or other sources of electrical signals.

FIG. 5 illustrates another example pericardial modification device 500.Pericardial modification device 500 is a forward-cutting device.Pericardial modification device 500 includes a shaft 510, a collar 520,and an incisor 530. In some implementations, pericardial modificationdevice 500 is used with a guidewire 440 and an introducer sheath 450.Collar 520 is coupled to shaft 510. In some embodiments, collar 520 iscoupled to a distal end portion of shaft 510. Collar 520 defines acentral opening in which guidewire 440 can be slidably received. Inalternative embodiments, shaft 510 can include a lumen which canslidably receive guidewire 440 (as shown in FIG. 6 , for example). Insome such embodiments, collar 520 is omitted.

Incisor 530 is coupled to shaft 510. In some embodiments, incisor 530 isfixedly coupled to shaft 510. In some embodiments, incisor 530 ispivotably coupled to shaft 510. For example, in some embodiments incisor530 is pivotable in relation to shaft 510 and spring-biased to pivotoutward to the configuration as shown. However, when incisor 530 islocated within sheath 450, incisor 530 can be pivoted closer to shaft510 to provide a lower profile. In some embodiments, upon emergence fromsheath 450, spring-biased incisor 530 can self-pivot outward from shaft510 to the configuration as shown. Incisor 530 can include one or moresharp edges. In some embodiments, incisor 530 includes a sharp tip thatcan penetrate tissue such as the pericardium. In some embodiments,incisor 530, or shaft 510, or both, may include one or moreelectrocautery electrodes to facilitate modification of the pericardiumand/or cauterization of tissue. In some embodiments, pericardectomydevice 500 can also include nerve stimulation capabilities to assistwith identification of nerve locations. In some embodiments, pericardialmodification device 500 is steerable.

In some embodiments, incisor 530 and/or shaft 510 may include one ormore electrodes 534 and 512 respectively to assist with nerveidentification. For example, in some implementations electrodes 534and/or 512 may be useful for identification of the location of phrenicnerves and other nerves. Alternatively, or additionally, electrodes 534and 512 may be used to sense electrical signals from the left atrialappendage and/or other sources of electrical signals.

FIG. 6 illustrates another example pericardial modification device 600.Pericardial modification device 600 is a reverse-cutting device.Pericardial modification device 600 includes a shaft 610 and an incisor630. In some implementations, pericardial modification device 600 isused with a guidewire 440 and an introducer sheath 450. In the depictedembodiment, shaft 610 defines a central lumen in which guidewire 440 canbe slidably received. In some alternative embodiments, a collar can beused to couple with guidewire 440 rather than, or in addition to, thecentral lumen in shaft 610. The distal end of pericardectomy device 600includes an atraumatic tip. In some embodiments, pericardialmodification device 600 is steerable. For example, in some embodimentsthe distal tip portion of pericardial modification device 600 issteerable. In some such embodiments, steerage of the distal tip portionof pericardial modification device 600 can be used to create a tent inthe pericardium. Thereafter, a wire can be made to emerge from thedistal tip portion of pericardial modification device 600 such that thewire can pierce the pericardial tissue. In some embodiments, the wire isan electrocautery wire and the wire can be used to sever the pericardialtissue after the puncture is made. In some embodiments, incisor 630 canbe used to sever the pericardial tissue after the puncture is made.

Incisor 630 includes a tip 632 and a cutting portion 634. In someembodiments, tip 632 and/or cutting portion 634 are sharpened to enablepiercing and/or shearing of tissue, such as pericardial tissue. In someembodiments, tip 632 and/or cutting portion 634 are electrocauteryelectrodes that can separate and/or cauterize tissue, such aspericardial tissue. In some embodiments, pericardial modification device600 can also include nerve stimulation capabilities to assist withidentification of nerve locations. In some embodiments, pericardialmodification device 600 is steerable.

FIG. 7 illustrates another example pericardial modification device 700.Pericardial modification device 700 includes a shaft 710 and anelectrocautery portion 730 that is disposed near the distal end portionof shaft 710. The distal end of pericardial modification device 700includes an atraumatic tip. Electrocautery portion 730 can be used toseparate and/or cauterize tissue, such as pericardial tissue. Shaft 710can be steerable in some embodiments. Shaft 710 can be flexible in someembodiments.

Pericardial modification device 700 can also include aspects that assista clinician to determine an orientation of electrocautery portion 730,so that electrocautery portion 730 can be positioned against the tissueto be severed. To accomplish that, in some embodiments a sensingelectrode (not shown) can be included on shaft 710. The sensingelectrode can be disposed on side of shaft 710 that is opposite fromelectrocautery portion 730. The sensing electrode can be used to senseelectrical signals from the surface of the heart. When the sensingelectrode detects such signals, it can be deduced that electrocauteryportion 730 is positioned opposite of the surface of the heart and,hence, against the pericardial tissue as desired. In some embodiments,fluoroscopy can be used to visualize the orientation of electrocauteryportion 730. In some such embodiments, one or more radiopaque markerscan be included on shaft 710 to facilitate such visualization of theorientation of electrocautery portion 730 in relation to the surface ofthe heart and the pericardium.

FIGS. 8A-8F are a series of illustrations depicting a pericardialmodification procedure in accordance with some embodiments providedherein. The pericardial modification procedure is performed using anexemplary pericardectomy system 800 on a heart 20 that has a pericardium22. Pericardectomy system 800 represents any of the examplepericardectomy devices and systems provided herein, and/or combinationsthereof. For example, while pericardectomy system 800 does notillustrate a grasping device for grasping and manipulating thepericardial tissue, one or more grasping devices may be included in someembodiments. It should also be understood that while FIGS. 8A-8F showthe incision and removal of a particular portion of pericardial tissue(orientated on a particular portion of heart 20), other portions andlocations of pericardial tissue can be incised and/or removed using thesame or similar pericardial modification procedure techniques asillustrated here. For example, in another example implementation thepericardial tissue constraining the apex of heart 20 can be modified by,for example, by incision and/or removal (refer also to FIGS. 2A-2D foradditional examples). The pericardial modification procedure isperformed while avoiding trauma to the epicardial surface of heart 20 aswell as the phrenic nerves.

In FIG. 8A, a delivery sheath 810 of pericardectomy system 800 is shownafter having been partially inserted through an incision to pericardium22. In this orientation, the distal tip portion of delivery sheath 810is within the pericardial sack and adjacent to the surface of heart 20.

In FIG. 8B, a guidewire 820 has been advanced from sheath 810.Advancement of guidewire 820 can be performed using fluoroscopy or otherimaging modalities.

In FIGS. 8C and 8B, a pericardial modification device 830 is beingadvanced over guidewire 820. Pericardial modification device 830 iscreating an opening 25 a and 25 b in pericardium 22.

In FIGS. 8E and 8F, pericardial modification device 830 has beenretracted into sheath 810. The openings 25 c and 25 d in pericardium 22are enlarged as desired. In some embodiments, an additionalgrasping/cutting device is used to remove the pericardial tissue toarrive at the configuration shown in FIG. 8F

With reference to FIG. 9 , a graph 900 of left ventricular end diastolicvolume 910 (on the x-axis) versus left ventricular end diastolicpressure 920 (on the y-axis) is provided. The lines 930, 940, and 950are the results from acute experiments using four normal dogs. Theseexperiments were performed to verify the acute benefits ofpericardiectomy, and to explore whether a limited pericardial incisionmight provide similar benefit to complete pericardial resection. Leftventricular pressures and volumes were measured at baseline (the lowerendpoint of each line 930, 940, and 950) and after rapid saline loading(the upper endpoint of each line 930, 940, and 950). Line 930 shows theleft ventricular pressure and volume with the pericardium intact. Line940 shows the left ventricular pressure and volume after a single linearleft lateral pericardial incision. Line 950 shows the left ventricularpressure and volume after complete pericardiectomy.

It can be seen that the left ventricular diastolic pressure-volumerelation shifted rightward indicating improved compliance withperformance of the pericardial modification procedure techniquesprovided herein. A significant amount of this benefit was achieved withthe single linear incision over the left lateral pericardium asrepresented by line 940. Note that the magnitude of increase in leftventricular filling pressures with saline bolus (700 ml) was lower fromthoracotomy to pericardial incision to full pericardiectomy. There was aslight creep upward in left ventricular end diastolic pressures at there-baseline state prior to the final saline loading (after fullpericardiectomy), likely due to the additive effect of receivingmultiple serial boluses to increase circulating plasma volume. Overall,the increase in left ventricular pressure per increase in leftventricular volume with saline load decreased progressively from line930 with the pericardium intact (0.90±0.22 mmHg/ml) to line 940 with thepericardial incision (0.44±0.13, p=0.04 vs. intact) to line 950 with thefull pericardiectomy (0.28±0.24, p=0.006 vs. intact, p=0.3 vs.incision).

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinvention or of what may be claimed, but rather as descriptions offeatures that may be specific to particular embodiments of particularinventions. Certain features that are described in this specification inthe context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described herein asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various system modulesand components in the embodiments described herein should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single product or packagedinto multiple products.

Particular embodiments of the subject matter have been described. Otherembodiments are within the scope of the following claims. For example,the actions recited in the claims can be performed in a different orderand still achieve desirable results. As one example, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

1.-10. (canceled)
 11. A method for treating diastolic heart failure of apatient, the method comprising: creating multiple openings in a parietallayer, and only in the parietal layer, of a pericardial tissue of thepatient by slitting, expanding, tearing, cauterizing, cutting, or insome other fashion modulating or otherwise modifying the parietal layer;and removing a portion of the parietal layer of the pericardial tissueof the patient, wherein the creating of the multiple openings reducespressure exerted by the pericardial tissue on a heart of the patient.12. The method of claim 11, further comprising probing to ascertain alocation of a phrenic nerve.
 13. The method of claim 11, wherein themultiple openings in the pericardial tissue of the patient are createdusing a transcatheter device.
 14. The method of claim 13, wherein thetranscatheter device includes one or more electrocautery electrodes. 15.The method of claim 11, further comprising using a grasping device tomanipulate the pericardial tissue of the patient.
 16. The method ofclaim 11, wherein the multiple openings in the pericardial tissue of thepatient are multiple incisions.
 17. The method of claim 11, furthercomprising inserting a guidewire between the pericardial tissue and asurface of the heart of the patient.
 18. The method of claim 17, furthercomprising advancing a pericardial modification device over theguidewire.
 19. The method of claim 18, wherein the pericardialmodification device is configured to shear the pericardial tissue of thepatient.
 20. The method of claim 18, wherein the pericardialmodification device is configured to cauterize the pericardial tissue ofthe patient.
 21. A method for treating diastolic heart failure of apatient, the method comprising: creating an opening in a visceral layer,and only in the visceral layer, of a pericardial tissue of the patient,without modifying or modulating a parietal layer of the pericardialtissue of the patient; wherein the creating of the opening reducespressure exerted by the pericardial tissue on a heart of the patient.22. The method of claim 21, further comprising removing a portion of thevisceral layer of the pericardial tissue of the patient.
 23. The methodof claim 21, wherein creating the opening in the visceral layer is donewithout fully or partially removing the parietal layer of thepericardial tissue of the patient.
 24. The method of claim 21, whereincreating the opening in the visceral layer is done by usingradiofrequency or direct current energy.
 25. A method for treatingdiastolic heart failure of a patient, the method comprising: creating anincision in a parietal layer, and only in the parietal layer, of apericardial tissue of the patient; inserting a delivery sheath within apericardial sac through the incision, the delivery sheath comprising aguidewire and a pericardial modification device; advancing thepericardial modification device over the guidewire, within thepericardial sac; and using the pericardial modification device to createan opening in the parietal layer, and only in the parietal layer, fromwithin the pericardial sac, wherein creating the opening in the parietallayer reduces pressure exerted by the pericardial tissue on a heart ofthe patient.
 26. The method of claim 25, wherein using the pericardialmodification device to create the opening in the parietal layercomprises puncturing an inner wall of the parietal layer that is incontact with a pericardial fluid, through an outer wall of the parietallayer.
 27. The method of claim 25, wherein the incision in the parietallayer is created near a subxiphoid access point of the patient.
 28. Themethod of claim 25, wherein the opening in the parietal layer is createdby using an incisor that is pivotably coupled to a shaft of thepericardial modification device.
 29. The method of claim 28, furthercomprising slidably receiving the guidewire in a central opening definedby a collar of the pericardial modification device prior to advancingthe pericardial modification device over the guidewire.
 30. The methodof claim 28, further comprising slidably receiving the guidewire in alumen defined by the shaft of the pericardial modification device priorto advancing the pericardial modification device over the guidewire.